WASHINGTON (CNN) -- The Bush administration has failed to provide a realistic assessment of how much the war in Iraq will cost taxpayers, lawmakers charged Wednesday.

That charge, leveled by Democrats and Republicans, came as Pentagon officials spent a second day on Capitol Hill talking about the situation in Iraq.

At a hearing of the House Armed Services Committee, several lawmakers suggested the administration was avoiding committing to any firm costs until after the general election in November.

But late Wednesday, the White House rebuffed charges that it was holding off on asking for more money to pay for the Iraq war for political reasons, and conceded a request for an additional appropriation may have to be made before the November election.

At issue is how much money will be needed to fund the war after October 1, the start of the 2005 fiscal year.

At the House Armed Services Committee hearing, Republican Rep. Curt Weldon of Pennsylvania pressed the Pentagon to work on a supplemental budget request so it's clear what the armed forces need.

"My request is ... that we work toward a supplemental and not wait until the election's over, but that we be serious about what is needed," Weldon said. "I want to give the Army the equipment they want."

President Bush has proposed a $401.7 billion budget for the Defense Department for the upcoming fiscal year, according to a White House breakdown on the 2005 request.

But Democratic Rep. John Spratt of South Carolina said the administration's military budget is "totally out of sync with reality."

The Bush administration has funded the wars in Iraq and Afghanistan with supplemental appropriations that are not included in its budget requests. Congress has passed two of those measures, totaling more than $160 billion, since the March 2003 invasion.

"They haven't asked for one single penny for next year for Afghanistan and Iraq. Give me a break," Sen. Joseph Biden of Delaware said on NBC's "Today" show.

"Why aren't they asking for it? They don't know? We already know it's going to cost at least a minimum of $60 billion to keep the troops there," said Biden, the ranking Democrat on the Senate Foreign Relations Committee.

Biden said that cost does not include any reconstruction funds.

Republican Sen. Chuck Hagel of Nebraska told NBC that the administration needs to "be honest with the Congress, be honest with the American people."

"Every ground squirrel in this country knows that it's going to be $50 billion to $75 billion in additional money required to sustain us in Iraq for this year," said Hagel, a member of the Senate Foreign Relations Committee, which also held hearings on Iraq.

Gen. Richard Myers, chairman of the Joint Chiefs of Staff, said the decision to keep about 20,000 U.S. troops in Iraq for an extra three months could add as much as $700 million to the cost of the war.

"Additional time in Iraq is going to cost us more money," Myers said. "We are working those estimates right now."

April has become the deadliest month for U.S. forces since the war began. On Wednesday, the southern Iraqi city of Basra, which has been mostly quiet, was the scene of five suicide bombings. (Full story)

With the cost of the war being driven up by intensified military operations and a decision to keep more troops in Iraq, adminstration officials conceded Wednesday that the money could run out sooner, perhaps as early as September.

That would require the administration to reverse course and ask Congress for more money before the election.

White House press secretary Scott McClellan said that while the administration did not expect to submit a request for more money this year, he did not rule out the idea.

'Mission must match the resources'

Hagel raised eyebrows Tuesday when he suggested the United States may need to reinstitute the draft.

On Wednesday, he said he was not advocating a return to military conscription, which ended in 1973 -- but the government "should start realistically exploring what our options are" and should consider some mandatory national service.

"If we, in fact -- as the president says and I agree -- are in a generational war here against terrorism, it's going to require resources. The mission must match the resources," said Hagel, who was an infantryman in Vietnam.

"The second question here is: Who is doing all of the fighting? This is also a societal issue. Should we continue to burden the middle class, who represents most all of our soldiers, and the lower-middle class?"

But House Majority Leader Tom DeLay of Texas said the chances of Hagel's proposal passing Congress were "none -- absolutely none."

Biden, who supported the 2002 congressional resolution that gave Bush the authorization to go to war, said the conflict so far is "not a shared burden."

"The biggest problem we've had from the beginning of this war is the president goes to war saying that it was going to be a major war, gives the largest tax cut in history, says to everybody, 'Don't worry, be happy' -- but by the way, we are going to send all of these reservists and all these National Guard folks for a lot longer than we thought," he said.